A microelectronic device with a high voltage component having a high voltage node, operable at a potential greater than 100 volts, may have a thin lower-bandgap dielectric layer between the high voltage node and a main dielectric which is several microns thick separating the high voltage node from low voltage components. The lower-bandgap dielectric layer, with a thickness commonly less than 10 percent of the thickness of the main dielectric, has a bandgap energy less than the main dielectric, and provides reliability for the main dielectric by reducing peak electric fields at corners of the high voltage node. However, the lower-bandgap dielectric layer supports other reliability degradation mechanisms which undesirably limit overall reliability of the microelectronic device.